Teratocarcinoma cell lines of both murine and human origin provide a unique model for developmental studies. In culture, these cell lines can be shown to form embryo-like structures and to possess morphological, chemical and antigenic similarities to the preimplantation embryo. Mouse teratocarcinoma can be placed back into the normal mouse blastocyst, and participate in normal developmental processes. Preliminary evidence indicates that aggregation induced developmental changes occur in human teratocarcinoma cell lines, and some of these changes can be measured by glyclipid expression. Glycolipids have for a long time been implicated in cell-cell recognition. Properties of glycolipids are believed to include: receptors for biologically active molecules, regulators of cell growth, and the ability to act as recognitions structures for cellular interactions during differentiation. Our long term objective is to obtain a better understanding of the functional properties of glycolipids during the recognition phenomena which take place in differentiating teratocarcinoma cells. This will provide a better understanding of events taking place during both normal and abnormal embryogenesis. To this end, we plan to continue a multi-faceted attack on this problem. First, we will isolate and characterize as many teratocarcinoma glycolipids as possible, using recently developed, highly sensitive methods which include high pressure liquid chromatography and mass spectrometry. Secondly, we will prepare mono-specific antibodies (polyclonal and mono-clonal) to those glycolipids which appear to have relationships with changing morphological biological, or biochemical properties of the cell lines. Thirdly, we will study the functional properties of these molecules by analyzing the effects in culture of 1) the glycolipids; 2) antibodies to the glycolipids; 3) differentiation inducing drugs such as retinoic acid on the expression of these glycolipids in association with the morphological and biological properties of these cells.